1. Field of the Disclosure
Example embodiments of the present disclosure relate generally to a laser scan unit for an image scanning device, and more particularly to an adjustable minor motor mounting for a laser scan unit.
2. Description of the Related Art
Multibeam and single beam laser scanners typically include a housing for holding the scanner's optical components that is constructed from a thermoplastic. Such thermoplastic housings disadvantageously shrink non-uniformly during the molding and subsequent cooling process in the manufacture of the housing. The inconsistencies associated with the molding and cooling of these parts creates two primary issues.
First, part-to part dimensional variation of features for mounting sensitive optical components, such as mirrors and lenses, creates the need for assembly adjustment mechanisms during production as well as for additional components. Second, during normal operation of electrophotographic printers, the fuser assembly, the laser scanner motor and other printer components and assemblies may create heat. As the thermoplastic housing heats, it expands thermally at two different coefficient of expansion based rates: parallel to the flow and fiber direction of the plastic during injection molding, and perpendicular to the flow and fiber direction of the plastic. The complex shape and features of the housing design, with a multitude of flow disruptions and directions, do not expand uniformly when heated, causing the part to warp or change shape along with the absolute expansion of the housing. This change of size and shape of the housing, which locates the critical laser pointing and focal elements, creates print quality issues associated with change of spot size and location of the laser image on the photoconductive drum, primarily color to color registration of the four color planes (CMYK).
One possible alternative to address the above-mentioned issues is having the housing formed from a metal. However, one of the challenges to the use of a metal housing is the fairly large tolerance that needs to be allowed. For example, the accepted industry norm for boss heights in drawn metal is significantly higher as compared to one constructed from thermoplastic: 0.250 mm for drawn metal vs. 0.05 mm for plastic over a 40 mm width. Tolerances associated with mirror motor mounting and planarity relative to the metal housing and the rest of the optical components are relatively important because the mirror motor is very early in the optical path of a laser scanner such that any error is magnified significantly at the end of the optical path. For example, any angular error is doubled because it is a mirror.
Based upon the foregoing, a need exists for an improved laser scan unit for an imaging device.